题目内容：
阅读短文，回答题。C．IQ-gene
1 In the angry debate over how much of IQ comes from the genes that children inherit from parents and how much comes from experiences, one little fact gets overlooked： no one has identified any genes ( other than those that cause retardation) that affect intelligence. So researchers led by Robert Plomin of London's Institute of Psychiatry decided to look for some. They figured that if you want to find a “ smart gene, ” you should look in smart kids. They therefore examined the DNA of students like those who are so bright that they take college entrance exams four years early — and still score at Princeton-caliber levels. The scientists found what they sought. “ We have，” says Plomin，“ the first specific gene ever associated with general intelligence. ”
2 Plomin's colleagues drew blood from two groups of 51 children each, all 6 to 15 years old and living in six counties around ClevelanD．In one group, the average IQ is 103. All the children are white. Isolating the blood cells, the researchers then examined each child's chromosome 6. Of the 37 landmarks on chromosome 6 that the researchers looked for, one jumped out 5 ： a form of gene called IGF2R occurred in twice as many children in the high-IQ group as in the average group — 32 percent versus 16 percent. The study, in the May issue of the journal Psychological Science, concludes that it is this form of the IGF2R gene that contributes to intelligence.
In the beginning of paragraph one we are told that scientists can not agree ______. A．how much of IQ comes from intelligence.
B．how many children inherit genes from parents.
C．how much of IQ comes from genes.
D．how many children learn by experience.
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